Leather drying machines



April 15, 969 R. J. ARCHER 3,438,137

LEATHER DRYING MACHINES Y Filed Oct. 12, 1966 Sheet of 5 April 15, 1969 R. J. ARCHER LEATHER DRYING MACHINES Sheet Filed Oct. 12, 1966 United States Patent 3,438,137 LEATHER DRYING MACHINES Richard John Archer, Luton, England, assignor to E. W. Hudson, Limited, Luton, England, a British company Fiied Oct. 12, 1966, Ser. No. 586,093 Claims priority, application Great Britain, Oct. 21, 1965, 44,649/ 65 Int. Cl. F26]: 25/06, 3/20 US. C]. 34-92 5 Claims ABSTRACT OF THE DISCLOSURE The invention is concerned with providing a platen structure for drying machines. The platen structure is particularly useful in drying machines for drying leather and the like under vacuum and includes a rigid box structure having a metal sheet which forms a platen surface positioned on an open side of the box structure. A heating chamber is provided within the box and a side of the box is developed as a vacuum hood which may be placed over another platen surface. A plurality of the box structures may be held in stacked relationship thereby providing a plurality of platen surfaces, heating chambers and vacuum hoods whereby a plurality of drying stations are provided.

This invention relates to drying machines and more particularly to platen structures therefor. The invention is particularly suitable for leather drying machines.

A leather drying machine basically comprises a platen surface on which the skin to be dried is slicked, means for heating the platen surface to provide drying heat and means to evacuate the space above the platen to assist the extraction of moisture from the skin and to remove the moisture thus extracted.

Platen structures have previously been constructed of mild steel having a chromium plated platen working surface, provision being made under the surface for the circulation of heated water. Previous constructions have necessitated a platen surface which is of the order of a quarter of an inch in thickness and in fact this thickness has in many cases been considerably increased beyond this. Thus difiiculty has been experienced due to the length of time required to heat the platen surface. Since it is essential that the heating of the skin must take place below a predetermined temperature, which may vary with the type and size of the skin being dried, it has been found essential that the water supplied for heating must at no time exceed this predetermined temperature so as to avoid hot spots at the platen surface. Due to the thickness of the platen surface, heat transfer between the water and the skin is far from ideal. Since the drying time with a fixed temperature depends to a large extent on this heat transfer, relatively long drying times have been necessary.

Once the platen surface has heated up, it would be uneconomical to cool it when removing the dried skin and replacing it by a wet one. Thus the operator has to work on a heated platen surface which may well be in the region of 180 F. or higher. Because of the thickness of the platen surface, the heat retained by it will be comparatively large and therefore, when the supply of heat is removed after a drying operation, only a relatively small amount will be lost by radiation and thus the platen surface will remain hot throughout.

The application of a skin to a hot platen increases the difficulties of the operator as it tends to some extent to cause the skin to roll up. Even if a cooling medium were used, the time which would be taken to cool the surface to a reasonable temperature would be prohibitive as would the reheating time and the cost of reheating.

3,438,137 Patented Apr. 15, 1969 The normal construction of a platen is somewhat expensive and should the surface become worn or damaged the platen would have to be replaced or undergo extensive repairs, thus rendering the machine inoperative for a considerable space of time.

The present invention seeks to obviate or substantially reduce the difiiculties and disadvantages of usual platens by providing a platen with good heat transfer characteristics and relatively economical repairability.

According to the invention a platen structure for a leather drying machine comprises a rigid box structure being enclosed on all sides except one, a sheet of metal forming the platen surface resting on the open side and means for supplying heating fluid to the interior of the box so as to enable it to contact the inner side of the metal sheet.

Preferably the metal sheet is a sheet of stainless steel or stainless/mild steel laminate. Where the platen structures are to be used in stacks, the underside of the structure is formed as a vacuum hood to co-operate with the surface of the adjacent platen structure. This would apply to all the platen structures with the exception of the one at the bottom of the stack, the top of the stack being provided with a separate vacuum hood.

One embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which:

FIGURE 1 is a side elevation of a leather drying machine having a platen structure in accordance with the invention;

FIGURE 2 is a plan view of the platen structure with the stainless steel sheet removed; and

FIGURE 3 is an end elevation of a stack of platen structures in greater detail.

Referring to FIGURE 1, a leather drying machine arrangements 2 and control gear 3. Thus the learther drying machine will only be described in relation to consists basically of a platen assembly 1, transfer the platen structure. The leather drying machine shown has a stack of six platen structures 4, 5, 6, 7, 8, and 9 containing five platen surfaces 10, 11, 12, 13 and 14 consisting of steel sheets.

Referring now particularly to FIGURE 3, each platen structure has a rigid frame 15 of U-section, the interior of the frame being divided up into upper, middle and lower sections 16a, [1 and c by means of a metal sheet 17 and a rubber sheet 18. In the platen structures 5 to 8 the upper section 16a is used for platen surface heating and the lower section 16c provides a vacuum hood for the platen surface there-beneath. The middle section 16b serves only as a spacer between upper and lower sections 16a and 16b. Platen structure 9 has only the vacuum hood portion 16c in use, the sheet 17 being omitted, and platen structure 4 has only the platen surface heating portion in use, the sheet 18 being omitted.

Each vacuum hood portion 16a is rendered airtight by means of the rubber sheet 18 attached to the frame 15 and 19, and is provided with three gauze sheets indicated at 26 (see particularly enlarged inset at 21) which provide a spacing for the sheet 18 so that it does not contact the skin being dried and allows moisture to be extracted therefrom.

Locating pins 22 are provided at opposite corners of each platen structure which pass through apertures in the platen structure above and in the stainless steel plate forming the platen surface.

Referring now to FIGURE 2, there is shown the platen structure 5 from above, the sheet 11 having been removed to disclose the heating section 16a thereof. The sheet 17, which forms the bottom of the heating section is bolted to the frame 15 and supports a platen surface supporting structure. This supporting structure consists of a plurality of tubes 23 on which bars 24 are positioned, the tubes passing through apertures in the bars and being welded thereto. The surface sheet 11 is supported by these bars 24, the bars being provided with additional apertures 25 FIGURE 3 to allow steam circulation. The edges of the sheet 11 are of course supported by the frame 15. As can be seen, the locating pins 22 have circular locating apertures at 27 and elongated apertures at 28 allow for expansion and contraction of the platen structure while permitting lateral alignment.

It will be understood that all the platen structures are constructed identically with the exception of the missing portions of platens structures 4 and 9.

Referring now to FIGURES 2 and 3 it will be seen that steam inlet pipes are provided at 29, extraction pipes for the hood at 30 and extraction pipes for steam control at 31. Four jack locators 32 are provided. The sheets 10 to 14 are provided with flange side members 33 for engagement by sheet extractors.

In order to provide sealing of the platen surface sheets of the platen structures, seals 36 are provided at the upper and lower edges of the frame.

Various modifications may be made to the above described embodiment without departing from the scope of the invention, for example, any number of platen structures may be used in a single machine, limited only by the practicability of the operation of the machine. If a small machine drying only one skin were required structures 4 and 9 only could be used.

I claim:

1. A platen structure for a drying machine comprising a plurality of rigid box structures each enclosed on all sides except one and held in stacked relationship, a sheet of metal forming a platen surface resting on each open side, a heating chamber formed within each of said box structures adjacent each of said sheets of metal, and means for supplying heating fluid to each of said heating chambers so as to enable the fluid to contact the inner side of each of said metal sheets, the side of each of said box structures opposite respective ones of each of said sheets of metal being recessed to form a vacuum hood suitable for placing over another platen surface, each vacuum hood being in sealed relationship with the platen surface of the adjacent box structure.

2. A platen structure according to claim 1, including an enclosed chamber within each of said rigid box structures between the heating chamber and the vacuum hood of the respective rigid box structures.

3. A platen structure according to claim 1, including a separate vacuum hood positioned over the platen surface of the rigid box structure at one end of the stack of rigid box structures, and a separate rigid box structure having a platen surface and a heating chamber formed within positioned at the other end of the stack of rigid box structures.

4. A platen structure according to claim 1, including a frame within each one of said rigid box structures supporting a respective one of said sheets of metal.

5. A platen structure according to claim 1, wherein each of said vacuum hoods comprises a rubber sheet and at least one gauze sheet attached to parts of a respective one of said rigid box structures.

References Cited UNITED STATES PATENTS 2,661,543 12/1953 Tyndall et al.

2,686,976 8/1954 H oughton 34-41 3,151,952 10/1964 Turato 3492 3,224,109 12/1965 Turato .34-92 3,253,351 5/1966 Bettanin 3492 3,321,842 5/1967 Bocciardo 34-162 XR 3,284,917 11/1966 Foote 34--145 XR JAMES W. WESTHAVER, Primary Examiner.

H. B. RAMEY, Assistant Examiner.

U.S. C1. X.R. 34-151 

